Clase 5 y 6 Semana 3

CAP 2: WORK STUDY AND ERGONOMIC

Prof. Ing. Héctor Fabio Bonilla Londoño Msc.

hfbonilla@javerianacali.edu.co
Ingeniería de Métodos 2019-1
Departamento de Ing. Civil e Industrial
 Introduction

Sections:
1. The Nature of Work

Chapter 1 2. Defining Work Systems

3. Types of Occupations

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Historical Figures Related to Work
 Industrial Revolution (1770’s)
 James Watt
 steam engine
 Henry Maudslay
 screw-cutting lathe

 (Factories)
 Machines started to replace workers
 Produce more quickly and accurately
 Specialization of labor
 Use of large numbers of unskilled labors who works long hours for low pay
(including women & children)

 Interchangeable parts manufacture

 Eli Whitney (1765-1825)
 produces 10000 muskets for the US government
 Standard parts
 Special tools, fixtures etc.
 Unique products replaces custom-fabricate products

 Mass production (assembly line)

 Henry Ford (1863-1947)
 Model T for less than $500 in 1916
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Historical Figures Related to Work
 Scientific management (late 1800s)

 Frederick W. Taylor (1856-1915)

 Father of scientific management

 Frank (1868-1924) & Lillian Gilbreth (1878-1972)

 Father (mother) of motion study
 All works are composed of basic motion elements (therbligs)
 There is one best method to perform a certain task.
 Cheaper by the Dozen

 Motion study (finding the best method to perform a task)

 Time study to establish work standards for a job
 Use of standards in industry
 Labor incentives (bonus payments for higher outputs)
 Use of data collection, record keeping, cost accounting

 The objective is to improve the (labor) productivity

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Work
 Is our primary means of livelihood

 Serves an important economic function in

the global world of commerce

 Creates opportunities for social interactions

and friendships

 Provides the products and services that

sustain and improve our standard of living

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 The Nature of Work
 Work is an activity in which one exerts physical and
mental effort to accomplish a given task or perform a
duty

 Task or duty has some useful objective

 Worker applies skills and knowledge for successful

completion

 The activity has commercial value

 The worker is compensated

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Work (Physics Definition)
 The displacement (distance) that an object moves in a
certain direction multiplied by the force acting on the
object in the same direction.
 W=F.d (Newton-meter)

 Units of measurement:
 Newton-meters (N-m) in the International System of Units
(metric system)

 Foot-pounds (ft-lb) in U.S. customary units

 Work is more than muscular applications.

 Combination of physical and cognitive work.

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 The Pyramidal Structure of Work
 Work consists of tasks

 Tasks consist of work elements

 Work elements consist of basic motion elements

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Task
 An amount of work that is assigned to a
worker or for which a worker is responsible

 Repetitive task – as in mass production

 Time required = 30 seconds to several
minutes

 Non-repetitive task – performed

periodically, infrequently, or only once
 Time required usually much longer
than for repetitive task

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Work Element
 A series of work activities that are logically
grouped together because they have a unified
function in the task

 Example: assembling a component to a base

part using several nuts and bolts

 Required time = six seconds or longer

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Basic Motion Elements
 Examples:
 Reaching for an object
 Grasping the object
 Moving the object
 Walking
 Eye movement

 A work element consists of multiple basic

motion elements

 Less than a second

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Pyramidal Structure of Work
 Extended to a worker’s career

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Importance of Time
 In many human activities, “time is of the
essence”
 In sports
 In daily living
 In business and industry
 In work

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Importance of Time in Business and
Industry

 New product introduction

 Product cost (reduced time means reduced
labor costs)
 Delivery time
 Overnight delivery
 Competitive bidding (proposals should be
submitted by a specific date)
 Production scheduling (being on time)

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Importance of Time in Work
 Time is the most frequently used measure of work (not
Newton-meter)
 How many minutes or hours are required to perform a
given task?
 Most workers are paid by the time they work
 Hourly wage rate
 Salary
 Time=Money
 Workers must arrive at work on time
 Otherwise his/her absence may handicap the rest of the
team
 Labor and staffing requirements computed in units of
time
 Aggeragate unit

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Work System Defined (manual,
machine system buraya)
 As a physical entity, a work system is a system
consisting of humans, information, and
equipment designed to perform useful work
 Results of the useful work contributes to the
production of a product or delivery of a service
 Examples:
 Worker operating a machine tool in a factory
 An assembly line consists of a dozen of workers at
seperate work stations along a moving conveyor
 Parcel service agent driving a delivery truck to make
customer deliveries
 Designer working at a CAD workstation
 A receptionist answering incoming phone calls

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
A Work System as a Physical Entity

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Work System Defined
 As a field of professional practice, work systems include:

 Work methods - analysis and design of tasks and jobs

involving human work activity
 Operations analysis & methods engineering

 Work measurement – analysis of a task to determine the

time that should be allowed to perform the task
 Time study
 Product costs
 Worker performance
 Worker requirements
 Standard time
 How long it takes to accomplish a given work
 (Time=Money)

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Work System Defined
 As a field of professional practice, work
systems include (cont.)

 Work management – organizational and

administrative functions that must be
accomplished to achieve high productivity and
effective supervision of workers
 Organizing workers
 Motivating workers
 Evaluating jobs
 Evaluating performances
 Compensating workers (labor wages)

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Comparisons: Industries and Workers
 It is convinient to group occupations into the
following four groups although there are more
types of occupations

1. Production workers
 Making products
 Manufacturing, construction, agriculture

2. Logistics workers
 Moving materials, products, people
 Transportation, distribution, material handling

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Comparisons: Industries and Workers
 It is convinient to group occupations into the following
four groups although there are more types of
occupations (cont.)

3. Service workers
 Providing service, applying existing information
knowledge, communicate
 Banking, retail, government, health care

4. Knowledge workers
 Creating knowledge, solving problems, managing
 Management, engineering, legal, consulting,
education

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Comparison of Work Characteristics

Physical activities Cognitive activities

Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Relative Percentages of Occupations in
the U.S. Workforce 1900-1998

TR 2007

28

26
54

46

In one century the proportions have reversed.

Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Productivity
 The level of output of a given process relative to the level of
input (output/input)
 Process can refer to
 Individual production or service operations
 Can be used in the context of a national economy
 Productivity is an important metric in work systems because
Improving productivity means
 saving scarce natural and human made resources
 worker compensation can be increased without
increasing the costs of products and services they
produce
 Products and services at lower prices for consumers which
improves standard of living
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Labor Factor in Productivity
 Labor itself does not contribute much to improving
productivity
 More important factors:
 Capital - substitution of machines for human labor
 Investing an automated production m/c to
replace a manually operated m/c
 Technology - fundamental change in the way
some activity or function is accomplished
 It is more than using a m/c in place of a human
worker
 A technologically more developed m/c replaces
the previous one.

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Examples of Technology Changes
Horse-drawn carts Railroad trains

Steam locomotive Diesel locomotive

Telephone operator Dial phone

Manually operated Numerically controlled

milling machine (NC) milling machine

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Increasing Productivity
 Important to recognize important gains in
productivity are more likely to be made
 By the introduction of capital and technology
in a work process
 Than by attempting to get more work in less
time out of the workers

 For example, in construction industry, mortar in

mixers pumped into molds rather than workers
mixing by shovels

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Manual Work System

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Worker-Machine System

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Automated System

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Some Definitions
 Work unit – the object that is processed by the work
system

 Workpiece being machined (production work)

 Material being moved (logistics work)
 Customer in a store (service work)
 Product being designed (knowledge work)

 Unit operations – tasks and processes that are treated

as being independent of other work activities

 As opposed to sequential operations (sequence of

operations required to manufacture a product or deliver a
service)

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Manual Work Systems
 Most basic form of work in which human body
is used to accomplish some physical task
without an external source of power

 With or without hand tools

 Even if hand tools are used, the power to operate
them is derived from the strength and stamina of a
human worker
 Hairbrush vs hair dryer

 Of course other human faculties are also

required, such as hand-eye coordination and
mental effort
Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Pure Manual Work
 Involves only the physical and mental
capabilities of the human worker without
machines or tools.
 Material handler moving cartons in a warehouse
 Workers loading furniture into a moving van without
the use of dollies
 Dealer at a casino table dealing cards
 Office worker filing documents
 Assembly worker snap-fitting two parts together

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Manual Work with Hand Tools
 Manual tasks are commonly augmented by use
of hand tools.

 Tool is a device for making changes to objects

(formally work units) such as cutting,
grinding,striking, sequeezing
 Scissor, screwdriver, shovel

 Tools can also be used for measurement

and/or analysis purposes

 Workholder to grasp or poisiton work units

Work Systems and the Methods, Measurement, and Management of Work
by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
 Manual Work with Hand Tools
 Machinist filing a part
 Assembly worker using screwdriver
 Painter using paintbrush to paint door trim
 QC inspector using micrometer to measure the
diameter of a shaft
 Material handling worker using a dolly to move
furniture
 Office worker writing with a pen

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Repetitive vs. Nonrepetitive Tasks
 Repetitive Task
 Work cycle is relatively short (usually a few minutes
or less)
 High degree of similarity from one cycle to the next

 Nonrepetitive Task
 Work cycle takes a long time
 Work cycles are not similar

 In either case, the task can be divided into

work elements that consist of logical groupings
of motions

Work Systems and the Methods, Measurement, and Management of Work

by Mikell P. Groover, ISBN 0-13-140650-7.
©2007 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.